In semiconductor technologies, backside illuminated image sensors (BSIs) are used for sensing a volume of light projected towards a backside surface of a substrate. During fabrication of BSIs, an ion implantation is applied to the backside of the substrate, and a laser annealing process is further applied to the backside of the substrate to activate the implanted dopant. Either a scan-type laser or a step-type laser may be used to perform the annealing process after the ion implantation. However, when the scan-type laser source is used, a periodic defect, such as fixed pattern noise (FPN), is introduced into the BSIs. Furthermore, both the scan-type laser and the step-type laser can induce laser boundary image issues. Improvements in backside illuminated image sensors and/or corresponding methods for manufacturing the same are desired.